For obvious reasons, it is vitally important in the industrial food processing industry to fully cook food products prior to packaging. Such food products may not be subjected to any further step or process for killing bacteria prior to consumption of the food. Moreover, the performance of an industrial food processing system, such as an oven, fryer, steamer, roaster, chiller, or freezer can be significantly impacted by physical attributes of the food product, such as the thickness of the food product. Often, food product thickness can vary between batches or can trend thicker throughout a production shift without detection by personnel. If, for example, a new batch of food product enters a cooking process, and the average thickness of the new food product is larger than the thickness of the prior batch, it is desirable to proactively control the thermal process to insure proper cooking. Such proactive control is not widely practiced today. Typically, the control process is largely reactive. When an undercooked or otherwise under processed food product is detected as it leaves a thermal processing station, personnel typically respond by manually adjusting process settings.
The temperature of the food product leaving the thermal processing station is typically measured manually by inserting a thermal couple probe into the processed food product hopefully at or near the mass center of the workpiece. However, it is difficult for personnel to accurately determine where the mass center of the workpiece is located. An additional difficulty and source of temperature measurement error exists in placing the temperature probe at the estimated center of the workpiece even if the operator believes that he or she has identified the mass center. Moreover, a further source of error occurs when the measuring tip of the probe is positioned in what is thought to be the mass center of the workpiece, but in actuality is a void in the workpiece. A slight change in the position of a thermal probe can result in a significant difference in the temperature reading achieved, especially if the temperature probe is placed into a void in the workpiece.
Moreover, typically, the number of workpiece samples that are actually selected for temperature measurement is relatively small in relation to the number of workpieces being processed. Such relatively small sample size can be a source of temperature measurement error.
In an effort to reduce the likelihood of food products not being fully cooked or otherwise not sufficiently thermally processed, the current food industry practice is to adjust the cooking or other thermal process so that the center of the thickest workpieces reaches a desired temperature. Such desired temperature typically is a temperature at which pathogens are instantaneously killed from the temperature of the food product. However, typically the desired temperature is higher than such kill temperature so that there is a desired confidence level that all of the food products have reached a sufficient temperature. Thus, the temperature to be achieved may be increased to a desired temperature of perhaps several standard deviations above the actual kill temperature. This approach can result in a significant proportion of the workpieces being overly-cooked or otherwise overly-processed, which causes a decrease in yield as well as a decrease in profit because the overcooking or overthermal processing drives off moisture from the food product, resulting in a reduction in the weight of the processed food product as well as its quality. Applicants estimate that eliminating the overcooking in a single process line can result in an economic savings of hundreds of thousands of dollars per year. This economic benefit arises from not having to cook or otherwise thermally process based on the thickest, largest, or otherwise maximum or extreme food product in the population being processed. Other benefits include (1) a reduction in labor required to monitor, control, and report on the process, (2) a reduction in unscheduled sanitation procedures of the thermal processing system, including the thermal processing station and the conveyance systems removing the food product to and from the thermal processing station, as well as (3) increased production line operational time.
Because improperly or underthermally processed food products present a high safety risk, a highly hygienic solution is desired to ensure that the food products are fully cooked or otherwise fully thermally processed. As such, it is desirable to have minimal equipment situated over the food product traveling to a thermal processing station, during thermal processing at the thermal processing station, as well as traveling away from the thermal processing station, unless the equipment in question operates at a cooking temperature, or is otherwise maintained at a highly hygienic state. Complex equipment located over food product being thermally processed presents a contamination hazard since contaminated droplets of water or other moisture can fall on the cooked or otherwise processed food product.
In an effort to at least partially automate the temperature measurement function of cooked or otherwise processed food products, “pick-and-place” robots have been contemplated. The envisioned systems and equipment are situated over the food product stream, are used to remove selected food products from the food product stream and then transmit the food products to a temperature measurement location or station, where manual temperature measurement of the selected food product takes place. Concerns about this solution may have prevented pick-and-place systems from being reduced to practice for thermal processes.
An approach that is approved by food safety regulations as an alternative to simply reaching a minimum pathogen kill temperature in a food product is to achieve a required level of reduction of pathogens in the food product. Such pathogens can be killed over time, with the rate of kill depending on the temperature of the food product achieved. If the temperature profile of the food product over time is known, then the level of pathogen killed in the food product can be determined. If such temperature profile can be determined with accuracy, then the thermal processing time for the food product may be sufficiently tailored to the food product in question, rather than having to take the potentially less efficient strategy of ensuring that the thickest food product has been heated to above the instantaneous kill temperature of the pathogens in question.